tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1/*
2 * linux/ioctl.h for Linux by H.H. Bergman.
3 */
4
5#ifndef _ASM_IOCTL_H
6#define _ASM_IOCTL_H
7
8/* ioctl command encoding: 32 bits total, command in lower 16 bits,
9 * size of the parameter structure in the lower 14 bits of the
10 * upper 16 bits.
11 * Encoding the size of the parameter structure in the ioctl request
12 * is useful for catching programs compiled with old versions
13 * and to avoid overwriting user space outside the user buffer area.
14 * The highest 2 bits are reserved for indicating the ``access mode''.
15 * NOTE: This limits the max parameter size to 16kB -1 !
16 */
17
18/*
19 * I don't really have any idea about what this should look like, so
20 * for the time being, this is heavily based on the PC definitions.
21 */
22
23/*
24 * The following is for compatibility across the various Linux
25 * platforms. The i386 ioctl numbering scheme doesn't really enforce
26 * a type field. De facto, however, the top 8 bits of the lower 16
27 * bits are indeed used as a type field, so we might just as well make
28 * this explicit here. Please be sure to use the decoding macros
29 * below from now on.
30 */
31#define _IOC_NRBITS 8
32#define _IOC_TYPEBITS 8
33#define _IOC_SIZEBITS 14
34#define _IOC_DIRBITS 2
35
36#define _IOC_NRMASK ((1 << _IOC_NRBITS)-1)
37#define _IOC_TYPEMASK ((1 << _IOC_TYPEBITS)-1)
38#define _IOC_SIZEMASK ((1 << _IOC_SIZEBITS)-1)
39#define _IOC_DIRMASK ((1 << _IOC_DIRBITS)-1)
40
41#define _IOC_NRSHIFT 0
42#define _IOC_TYPESHIFT (_IOC_NRSHIFT+_IOC_NRBITS)
43#define _IOC_SIZESHIFT (_IOC_TYPESHIFT+_IOC_TYPEBITS)
44#define _IOC_DIRSHIFT (_IOC_SIZESHIFT+_IOC_SIZEBITS)
45
46/*
47 * Direction bits.
48 */
49#define _IOC_NONE 0U
50#define _IOC_WRITE 1U
51#define _IOC_READ 2U
52
53#define _IOC(dir,type,nr,size) \
54 (((dir) << _IOC_DIRSHIFT) | \
55 ((type) << _IOC_TYPESHIFT) | \
56 ((nr) << _IOC_NRSHIFT) | \
57 ((size) << _IOC_SIZESHIFT))
58
59/* used to create numbers */
60#define _IO(type,nr) _IOC(_IOC_NONE,(type),(nr),0)
61#define _IOR(type,nr,size) _IOC(_IOC_READ,(type),(nr),sizeof(size))
62#define _IOW(type,nr,size) _IOC(_IOC_WRITE,(type),(nr),sizeof(size))
63#define _IOWR(type,nr,size) _IOC(_IOC_READ|_IOC_WRITE,(type),(nr),sizeof(size))
64
65/* used to decode ioctl numbers.. */
66#define _IOC_DIR(nr) (((nr) >> _IOC_DIRSHIFT) & _IOC_DIRMASK)
67#define _IOC_TYPE(nr) (((nr) >> _IOC_TYPESHIFT) & _IOC_TYPEMASK)
68#define _IOC_NR(nr) (((nr) >> _IOC_NRSHIFT) & _IOC_NRMASK)
69#define _IOC_SIZE(nr) (((nr) >> _IOC_SIZESHIFT) & _IOC_SIZEMASK)
70
71/* ...and for the drivers/sound files... */
72
73#define IOC_IN (_IOC_WRITE << _IOC_DIRSHIFT)
74#define IOC_OUT (_IOC_READ << _IOC_DIRSHIFT)
75#define IOC_INOUT ((_IOC_WRITE|_IOC_READ) << _IOC_DIRSHIFT)
76#define IOCSIZE_MASK (_IOC_SIZEMASK << _IOC_SIZESHIFT)
77#define IOCSIZE_SHIFT (_IOC_SIZESHIFT)
78
79#endif /* _ASM_IOCTL_H */
80